Tire grooving tool



Patented Sept. 3, 1935 UNITED STATES PATENT OFFICE TIRE GROOVING TOOL Dewey Edward Campbell, Detroit, Mich. Application March 6, 1933, Serial No. 659,762

3 Claims.

My invention relates to a tire grooving tool and more particularly to an electrically heated tool used for the purpose of grooving the tread of rubber tires which have worn in such a manner as to become substantially smooth.

Prior to my invention tire grooving tools have been used to cut grooves in the tread portions of a tire upon which the tread has worn in such a manner as to present a substantially smooth surface to the road. Such tools have been characterized by the use of a fixed knife or knives which cut the rubber while in an unheated condition. The general use of such tools was not found to be satisfactory as the cold knife could cut the cold rubber only through the use of a considerable amount of pressure exerted on the knife. This in turn dulled the knife rapidly and prevented satisfactory results from its use.

Other devices heretofore known have attempted to overcome this objection by providing a heated knife. This, however, has not been satis-= factory because the heat of the knife was rapidly dissipated upon its contact with the surface of the rubber and it was impossible to maintain a sufficiently hot condition in the knife to overcome the defects of a out the use of heat.

therefore,

It is, tion to adapted provide tool which operated with an object of my present invena tire grooving tool which is to heat the rubber in advance of the cutting knife, and to cut the rubber with a heated knife It is a further while in the heated condition.

object of my present invention to provide a tire grooving tool in which the grooving knife is adjustable relative to the tool in order to permit the use of the same knife for cutting grooves of difierent depths. It is a further object ofmy present invention to provide a tire grooving tool which is electrically heated'in such a manner as to permit the accurate cutting of the groove in the tire with a minimum of dulling action to the cutting edge of the knife blade.

These and various other objects, features of arrangement, construction and operation, are plainly shown and described and will be best understood by reference to the accompanying drawing, in which:

Fig. 1 is a side elevation of a tire grooving tool embodying my invention shown in operative position relative to a fragmentary section of an automobile tire;

taken on the line 2-2 of Fig. 1;

Fig. 3 is an end elevation taken on the line 3-3 of Fig. 1;

Fig. 4 is a fragmentary section of the knife element taken on the line 44 of Fig. 3.

Similar reference numerals refer to similar 5 parts throughout the several views.

Referring more in detail to the drawing, l0 designates a handle which may be formed of wood or other suitable non-heat-conducting material. An electric cord |l extends through the handle I0 and inside a hollow body portion |2 to which thehandle I0 is secured. An electrical heating element I3 is electrically connected with the cord H and is contained within a casing l4 adjacent the end of the body portion l2 and opposite its point of connection with the handle I0.

Secured to the casing l4 adjacent the heating element I3 is a screw-threaded plug l5, through which a cutting head l6 extends to a point of contact with the heating element I3. The cutting head It consists of 'an extending finger ll having a screw-threaded shank portion |8. Knife clamping elements I9 and are held in intimate coritact with the knife 2| and the extending finger II- by a screw-threaded member 22, which passes through the clamping elements I9 and 20 and the body of the finger H. The knife clamping elements i9 and 20 are also maintained in clamping relation relative to the knife j 2| by means of a second screw-threaded member 23 (Fig. 1), whichpasses through the elements l9 and 20 at a point adjacent the finger l1.

As shown in Fig, 3, the knife 2| is U-shaped in cross section and is sharpened as shown in Fig. 4 in such a manner as to present a cutting surface along its forward edge so as to cut a substantially U-shaped groove as it is moved relative to the surface of the tire.

In order to prevent overheating of the handle III, a plurality of vents 24 is provided in the member l2.

The operation of a device embodying my invention is as follows:

When a tire 25 has been worn smooth on its tread portion, it is possible to regroove the tread by use of a tire grooving tool embodying my invention. The cord H is secured to any suitable electric outlet and the heating element |3 heats the cutting head I6. This heats both the finger H and the knife 2|. After the head I6 is heated to a suitable temperature to soften the rubber to be grooved, thetool is applied to the surface of the rubber as shown in Fig. 1. As here shown, the finger l1 contacts the-surface of the rubber in advance of the knife 2| and as the tool 15.5

moved it continues to heat the rubber at its point of contact with the rubber, which is in advance of the knife 2|. The knife 2| extends below the lower surface of the finger I1 and its sharpened forward edge cuts into the surface of the rubber and forms a U-shaped groove therein as it is moved relative to the surface of the rubber. The knife 2| may be adjusted in such a manner as to permit cutting of the groove to any desired depth, this adjustment being accomplished by loosening of the screw-threaded elements 22 and 23 and the knife clamping elements 19 and 20, and moving the position of the knife relative thereto. I

The heat which is transmitted from the heating element I3 to the casing M in the member I2 is partially dissipated by reason of the ports 24, and the member I2 is maintained in a somewhat cooler condition by the circulation of air through the interior thereof through the ports 24.

While I have shown and described a tire grooving tool having a substantially U-shapedl knife 2|, 'itis apparent that any other desired shape of knife may be used, and I do not desire to be limited by this disclosure to a knife of the precise type shown herein. Likewise, various other types of heads may be employed for other purposes within the scope of my invention, and I do-nt' wish to be limited to the precise details of construction set forth, but desire to avail myself of all changes within the scope of the appended claims.

to heat said cutting head and including an elec-' trical resistance heating element, said cutting head including a groovingknife, a heated member adapted to contact a surface to be grooved in advance of said knife, and means for adjustably securing said knife to said heated member.-

2. A tire grooving tool including a handle, a

cutting head having an extending finger and an adjustable knife, a tubular body portion secured to said handle and said cutting head, and electrical heating means contained within said tubular body adjacent said cutting head and adapted to heat said extending finger and said adjustable knife whereby heat is conveyed to the surface to be grooved prior to cutting thereof by said adjustable knife.

3. A tire grooving tool including a handle, a cutting head having an extending finger and an adjustable knife, a tubular body portion secured to said handle and said cutting head, and means adapted to heat said extending finger and said adjustable knife whereby heat, is conveyed to the surface to be grooved prior to cutting thereof by said adjustable knife. I

. DEWEY EDWARD CAMPBELL. 

